The Democrat has a speaking engagement Friday at a veterans conference in Pittsburgh, according to Wolf spokesman J.J. Abbott.

When asked if Wolf's absence is an act of protest in any way, such as the 60 Democrats in Congress who are boycotting the inauguration, Abbott said no.

"The VFW conference is in Pittsburgh that day," he said.

It is not unusual for governors to miss inaugurations of presidents in opposing parties. For example, former Republican Gov. Tom Corbett missed President Barack Obama's second inauguration in 2012.

In addition to Wolf, four Democratic congressmen from Pennsylvania say they will not attend the inauguration. Brendan Boyle, Bob Brady, Mike Doyle and Dwight Evans say they are missing the event in solidarity with Rep. John Lewis, who Trump described as "all talk" and "no action."

Sen. Bob Casey, a Democrat from Scranton, still plans to attend the inauguration, but he said Wednesday he will vote 'no' on three of Trump's Cabinet picks.